Solenoid operation is pressure dependent - increase the supply pressure, and the solenoid requires more oomph to operate the valve. Poor solenoid operation with multiple solenoids would suggest an electrical problem, since a working solenoid on a working valve will have no problem opening the valve, as long as everything else is up to spec.

Fluke....

It may be a fluke..... someday.... for now it works and has worked perfectly, daily for 4 days... and counting... I bet there was a clog that cleared up on it's own or some other coincidence I am not aware of. Nevertheless I tried raising the pressure and it just stops working every time. I agree there may be some reason that the pressure is affecting the operation of the valve. It only happens on one of the 6 valves. By the way Superior recommends 40 - 60 psi on their troubleshooting literature....